This video does a great job explaining the people affected by the Holocaust.
The Holocaust began shortly after Hitler and his council came up with the "final solution". 11-14 million people died in Nazi concentration camps and 6 million of those people were Jews. The Holocaust was part of Hitlers plan to create a flawless race, targeting those who he thought inferior or a threat. When Germany surrendered it ended up taking more than a month before all the camps were liberated.